The very first five-pointed star may have been found by archeologists. Known as a pentagram, it is also historically Solomon's Seal, used by the King of Judah in the 10th century B.C.E. Solomon was the son of King David. Today the Star of David that adorns the flag of the nation of Israel is six-pointed but there are those who believe that originally the five-pointed star (pentagram) was used earlier.
As for Masonic barn stars, Masonic rituals vary within regions. One area may use Islamic icons for their rituals while another may use those based on Judaism and Christianity. One would probably have to ask individual barn owners what their star symbolized. Maybe in Kentucky we'd receive answers referring to the Civil War while in Indiana it could signify folk art. I pass one regularly out in front of a BBQ restaurant and I suspect it is meant to give one the impression of Texas. Stars are popular everywhere but depending upon how they are poised, sometimes you get the feeling it is a political or philosophical statement. I tried asking a Kentucky gentleman who lived across the street from a huge barn with a huge star on it. He acted like he didn't know what I was talking about so good luck with that. When you figure it out ... please let me know.
Suellen Ocean is the author of Secret Genealogy a how-to for tracing ancient Jewish ancestry and Secret Genealogy II, Uncovering the Jewish Roots of Our Christian Ancestors, both available at Amazon, B&N and Ocean-Hose. http://www.pacificsites.com/~oceanhose/